Finnish Patent Application No. 793473 relates to a safety spacer comprising an arm at one end of which there is a flat reflector and at the opposite end a fastening device which allows the arm to be swiveled and pivoted and comprises a fastening member attachable to a bicycle and, connected to it, a swiveling articulation member to which the arm can be pivotably attached by means of a pivot shaft which is substantially plane parallel with the reflector.
In this known arrangement the articulation member consists of one angle piece to which the arm and the fastening member are attached at different points by means of swivel shafts in such a way that these shafts are perpendicular to each other. On the bearing surfaces between the angle piece and the fastening member there are shoulders radial in relation to the swivel shaft and grooves corresponding to the shoulders, in order to lock the parts so that they cannot swivel. The articulation between the angle piece and the arm is freely swiveling friction joint.
The disadvantages of the above-mentioned safety spacer, known from Finnish Patent Application No. 793473, include the facts that two screws or similar fasteners are required for fastening all the parts of the spacer to a bicycle and that the shoulders formed on the above-mentioned bearing surfaces are susceptible to mechanical wear. The fact that the joint between the angle piece and the arm loosens with time constitutes a further disadvantage.